<p class="MsoNormal">I'm looking to step up to a sport plane from my Alpha 40 trainer. I have about 6mo flying experience of every weekend for about 4hrs each day and countless hours on the Phoenix flight sim with all kinds of planes. The price of glow is ridiculous at $105 for 4 gallons so I'm wanting to get a gas engine. I'm stepping up in a big way and need some advice.

Will the DLE20 be too much engine for the Pulse XT 60?
What size of prop would best suit me in the beginning? using APC props
Is it true that I will get radio interference with a gas engine? If so how do I go about fixing this?
How long would a 6v 4500mah NiMh battery last for the ignition source, or is there a better one?
Does the engine need to be mounted side ways or upside down? What is the benefit of this and can I mount it right-side-up?
Would the Hitech 5625MG servos be good enough for this plane? I'm not wanting to break the bank and these seam nice for the price/performance ratio.

I was originally looking at getting a FG-17 Saito but I've heard nothing but bad things from Saito's gas line. Are they really THAT bad of an engine?</p>

I think you're talking about a pretty good plan/plane. APC 17x6 should work nice, as well as the servos you're talking about. Engine inverted so stock exhaust will point down is the only reason. The engine could care less! If you're buying a battery, suggest you consider A123.

Optionally, you could run 2 batteries through 2 switches (providing redundancy) - then power your ignition module with those same batteries. Look into a voltage regulator and an optical switch (used to control power to ignition module from an extra channel on your radio). It's a lot to get your head wrapped around at first, but once figured out there isn't a much better way of going about it, and the cost/weight difference is not that much more than having separate batteries for your flight pack and ignition module.

Some guys are not real happy with the stock landing gear. Changing it out for something providing a little more ground clearance might be something to consider as well.

The Dle 20 engine is too much power for the Pulse XT 60. I also don't think you can turn a 17" prop with the stock landing gear on the Pulse. That engine would be perfect for the Pulse XT 20.

I am running a NGH GT17 gasser on a 60-sized Pulse XT right now. I even flew it today. It is a very nice match.

Jamesc43 is definitely right about the prop size. Iam running a 3-blade 14" on it with slightly taller than stock landing gear. Ihave some larger 4" wheels that I'm considering putting on the plane so I can use a larger prop.

While the GT17 is only 3cc's smaller than the DLE-20 (which I also own), I believe that the DLE-20 is much more powerful and I believe heavier. Even with a 2300 mAH2S A123 battery pack as far back under the wing as I can get it, the plane is still nose heavy. And that is after I cut out the lite-ply webbing behind the landing grear (which is also below the cockpit) to move the fuel tank to the C.G. (which included removing the stock 14oz (?)fuel tank and replacing it with an 8oz tank) and a fair amount of lead back at the tailwheel.

Here's your primary challenge:
A large enough prop that you don't over rev your DLE-20 and yet small enough that the prop isn't mowing the grass or grinding down on the runway
Not tearing those big wings off when you go WOT - the plane was not designed as a racer
Reinforcing the fuselage so that the vibrations and power doesn't tear it apart - Particularly in the original fuel tank area (over time I've done a number of reinforcements and repairs)

Don't get me wrong, I really like the Pulse XT. It is a lot of fun and flies really well with a small gas engine. But it flies best at modest speeds.

I even have a DLE-20 on a Ultra Stick 60, so I'm not shy about putting some power on small airplanes.

Have fun,
Paul


BTW - I think James was refering to the Pulse XT 120. I think that would be a good match too. I seem to remember that some people think that the tail feathers on the 120 are a little weak. I'm sure a search would turn up the specifics.

Skidman,

You are correct. I was referring to the Pulse XT 120.

I've had 2 Pulse XT 60s. They were powered by a OS 90 FX and MAS 13X8 prop. They flew great and floated like a dream. One was destroyed when
the right wing broke. It was a painfully crash. The second Pulse died when I applied to much power in a dive. It never recovered from the dive.

The entire Pulse line has weak tail feathers. The planes are fine as long as you do not overpower then. I've got a Pulse XT 40 with electric power. It's
not overpowered and flies great.

Yeah that's what I was afraid of...too much power. I'm not afraid to put more power in an airplane but I'm not looking to overspeed the airframe and rip the thing apart in-flight.

Does the Pulse XT40 fly as well as the 60 size? I was told that the 60size airplanes fly way better than their 40 size counter part. I was originally going to get an ultra stick but the wing area on the pulse was greater and it looks easier to fly. I haven't commited to anything yet so I'm open to suggestions. I don't want to go over $300 for the airframe or over a 60 size (anything over 6ft wing I wont be able to transport), but I want a gasser.

Thanks so far for yall's input so far.

Holy cow...... I see now I totally read that question wrong! After seeing reference to the DLE, my mind went right to the 120 sized plane! Didn't notice he had written 60!!! Totally spaced that until this moment!

I do know that if you can't transport more than a 72" wing, you have no problem. Those wings plug in on the 120, are nowhere near 72", and 300. is what that airframe sells for....

I have a Pulse 125XT that my daughter got me for christmas. Currently I'm running a Chinese 26cc gas engine in it and stock landing gear. As for balance, I have moved the stock fuel tank as far back as possible in the fuselage (under the instrument panel) with a 2200 2S lipo on a regulator in front of the fuel tank along with the ignition is the same compartment (under the hatch).

I have the servos mounted in their normal location with a 2200 3S lipo on a BEC regulator mounted to the servo plate between the servo's. The plane balances exactly where it's supposed to with no added weight anywhere.

I fly off a paved strip but I would HIGHLY suggest either different landing gear or adding some material to them to move the gear forward 1" especially if your planning on flying off grass. Landing have to be perfect otherwise you will get a prop strike (my 17" prop is now about a 16.25").

I can't say enough good about the plane/engine combo that I have. We have three of them in our club with the other two being powered by DLE20's. One has stock gear and the other has extensions where the axles were originally moving the wheels forward 1 1/2" and he has no problem taxing through the grass. I have to carry mine to the runway and start it there because trying to taxi through the grass it just becomes a half-pipe lawn mower. In the air the plane is about as perfect for sport flying as you could ask for. Not enough controls for for 3D but any advanced sport manuver is well within its ability and IMHO this plane would make a perfect second step plane for anyone wanting to move up. The 26cc is a little overpowered but thats what the throttle stick is for. I have not experienced any of the tail problems I have read about and suspect that a majority of those are caused by way more speed than the airframe was designed for. Full power dives are not what the designer had in mind and as such this plane is not intended for that type of flying. This is my new "every trip to the field " plane that goes regarless of what else I'm taking. I left the wings in two pieces and use the pins/wing bolts to hold it together as does one of the others flying at my club, so far no issues with the airframe on either. The wing is fat but the fuselage is very skinny so slowing down for landing requires so pre-planning otherwise it will float the full length of the runway and finally land in the next township.

Here's a link to the 125XT thread where I posted some pictures of my build.

<font color="#0000ff">http://www.rcuniverse.com/forum/fb.asp?m=10897447</font>

As for your original question about the 60 size with a DLE 20, In my opinion you would be way over-powered and have a lot issues to work through getting it to balance, getting enough prop clearance and keeping the vibration damage to a minimum. The 125 would be a lot better suited since there's about twice the airframe to dissipate the vibration and prop clearance in stock form is enough to get you flying and finally getting it to balance will not require a bunch of lead in the tail (which equals more speed which equals longer takeoff runs, longer final approaches and higher stall speed).

My Pulsr XT 40 is powered by the E-flite Power 46 motor, APC 13X6.5 prop, 5S 3750mah, Castle 80 amp ESC (overkill but that's what I had). I
was really afraid of getting a Pulse considering my previous issues but I thought if I didn't overpower it then I wouldn't have the issues. So far
it's true.

The Pulse XT 40 is a smaller plane and flies like it. I will says that it flies like it's bigger brothers only on a smaller scale. The bigger planes will
be more wind friendly and will ground handle (handle bumps and holes on the ground) better. We installed 4" air filled Dubro tires on our planes
because our field was rather rough. I used the stock tires of the Pulse 40 from the beginning and so far no issues.

I've never turned the landing gear around on any of my Pulses. I think if the CG is moved back far enough you will not have issues with nose
overs. I had the OS 91 FX in my Pulse XT 60s and only had to add 1/2oz of lead to the tail to get the CG on the suggested spot.

Thanks for the info guys. I might go with the 125 then so I can have a gasser. What is a good torque number to look for on a servo for a 125 size airplane? Any other info on what to reinforce or change while building it? I would like to do things right the first time and not have to tear it all apart later down the road. I do have some questions though from that other post that catflyer reffered me to.

What is the bennifit of using the pull-pull rudder since this plane isn't designed for speed?
What is the advantage of having the optical kill switch thing?

The Optical part is to provide isolation from the noise generated by the engine's ignition systems.

People who favor using an optical kill switch would say that by providing quick and dependable way to kill the engine from the transmitter it increases safety, and in the rare event of losing throttle servo control, the engine can be killed when the pilot choses, rather than when it runs out of gas.

The smaller number of nay sayers will point out that it an added failure point and that a properly tuned and setup engine can be killed by the throttle trim or a separate choke servo.


Personally, Ifly with an optical kill switch.

Paul

I have the Pulse 60 with a Saito FG-14 (14 cc) 4-stroke petrol engine. A perfect combination. A DLE 20 would be far and away excessive. There are a few Chinese 15cc 2-stroke gas engines which should be fine.

The Saito gas engines can be fiddly to tune, but have extraordinary economy if you fly a lot and are quiet. I also have the FG-20 with which I have had no problems. The Saitos are very expensive, but can pay for themselves in fuel costs even over a 2-stroke gas engine.

Many people have had problems with the Saito gas engines, but I'm not sure if it is the engines or people's expectations of them.

As for optical kill switches, I had never used one till a couple of weeks ago on one of my 50cc planes when the throttle servo mounting broke pulling the throttle almost wide open regardless of the setting. This plane had a manual choke setup so that was no good either and with a 20oz tank my fingers were frozen almost solid before it finally ran out of gas. This particular plane is a very lightweight plane and with the 55 in it vertical is unlimited so that was a heck of a lot of plane to keep up with till it quit.

Now ALL of my gas planes will have an optical kill switch before ever being started again.

As for the advantages of a pull-pull setup, I see none what so ever on this plane.

For servo's, I run all 100oz digital metal geared servos from China which cost me $9.00 a piece and now with over 50 of them in various planes of mine and others in my club the only failure to date was a burnt servo on a choke due to being mis-adjusted and stalled with the choke closed. Otherwise I would look into something like Futaba 3305's, not digital but plenty strong. Futaba does not recommend them for airplanes but I have seen 100's of them over the years in planes and have used 30+ myself and never had a problem.

Ignition battery, I think your original 4500mah would be way overkill. I have never used more than a 2200 on any ignition and thats been plenty of battery for an entire day at the field. I do however run all my ignitions on a 5 volt regulator regardless of the battery be it a 5 cell NiMh or 2 cell Lipo. There are regulators out there that will provide a clean 5 volts at 3 amps and the cost/weight is nothing. Maybe overkill but I would rather spend a few dollars on a regulator rather than take my chances at have a fully peaked pack be jst a couple 10ths of a volt over the threashhold on an ignition then have to spend $50 for a new one plus loose a day of flying.

While I love the sound and craftmanship of the Saito FG line, and the FG-20 is attractive at the current $399 price, Ican easily fly for over 20 minutes with an 8oz fuel tank with my NGH GT-17 2-stroke gas engine.With the FG-20 costing over $150 more, for a similar power output, even if the FG-20 used NO fuel, and gasoline cost $4.00/gallon (not counting oil but since we're assuming that the FG-20 doesn't use any fuel that seems fair), it would still take 300 full 8oz tanks for the fuel savings to pay for the added cost. That would mean between 60 - 100 hours of flight time - assuming that the FG-20 magically operates without any gasoline.

I would still love a FG-20 (at the lower price - not the $699 price). But it would be hard to make the fuel economy case against another <u>gasoline </u>engine. Against a similar displacement <u>glow </u>engine might be another story.